Low-Magnetic Field Critical Behavior in Strongly Type-II Superconductors

TL;DR

This paper introduces a novel theoretical framework for understanding the low-magnetic-field critical behavior of strongly type-II superconductors, involving a gauge transformation and potential new phase transitions.

Contribution

It presents a new description based on a gauge transformation of the Ginzburg-Landau theory, suggesting possible novel phase transitions involving vorticity and condensate formation.

Findings

Proposes a gauge-transformed Ginzburg-Landau functional for low magnetic fields.

Suggests the existence of a new phase transition involving zero vorticity.

Draws parallels with Higgs electrodynamics and liquid crystal transitions.

Abstract

A new description is proposed for the low-field critical behavior of type-II superconductors. The starting point is the Ginzburg-Landau theory in presence of an external magnetic field H. A set of fictitious vortex variables and a singular gauge transformation are used to rewrite a finite H Ginzburg-Landau functional in terms of a complex scalar field of zero average vorticity. The continuum limit of the transformed problem takes the form of an H = 0 Ginzburg-Landau functional for a charged field coupled to a fictitious `gauge' potential which arises from long wavelength fluctuations in the background liquid of field-induced vorticity. A possibility of a novel phase transition involving zero vorticity degrees of freedom and formation of a uniform condensate is suggested. A similarity to the superconducting [Higgs] electrodynamics and the nematic-smectic-A transition in liquid crystals is noted. The experimental situation is discussed.